// Dear ImGui: standalone example application for DirectX 12

// Learn about Dear ImGui:
// - FAQ                  https://dearimgui.com/faq
// - Getting Started      https://dearimgui.com/getting-started
// - Documentation        https://dearimgui.com/docs (same as your local docs/ folder).
// - Introduction, links and more at the top of imgui.cpp

// Important: to compile on 32-bit systems, the DirectX12 backend requires code to be compiled with '#define ImTextureID ImU64'.
// This is because we need ImTextureID to carry a 64-bit value and by default ImTextureID is defined as void*.
// This define is set in the example .vcxproj file and need to be replicated in your app or by adding it to your imconfig.h file.

#include "imgui.h"
#include "imgui_impl_win32.h"
#include "imgui_impl_dx12.h"
#include <d3d12.h>
#include <dxgi1_4.h>
#include <tchar.h>
#include <luisa/core/clock.h>
#include <luisa/runtime/context.h>
#include <luisa/runtime/stream.h>
#include <luisa/runtime/device.h>
#include <luisa/runtime/image.h>
#include <luisa/backends/ext/dx_config_ext.h>
#include <luisa/dsl/sugar.h>
struct FrameContext {
    ID3D12CommandAllocator *CommandAllocator;
    UINT64 FenceValue;
};

// Data
static int const NUM_FRAMES_IN_FLIGHT = 3;
static FrameContext g_frameContext[NUM_FRAMES_IN_FLIGHT] = {};
static UINT g_frameIndex = 0;

static int const NUM_BACK_BUFFERS = 3;
static ID3D12Device *g_pd3dDevice = nullptr;
static ID3D12DescriptorHeap *g_pd3dRtvDescHeap = nullptr;
static ID3D12DescriptorHeap *g_pd3dSrvDescHeap = nullptr;
static ID3D12CommandQueue *g_pd3dCommandQueue = nullptr;
static ID3D12GraphicsCommandList *g_pd3dCommandList = nullptr;
static ID3D12Fence *g_fence = nullptr;
static HANDLE g_fenceEvent = nullptr;
static UINT64 g_fenceLastSignaledValue = 0;
static IDXGISwapChain3 *g_pSwapChain = nullptr;
static HANDLE g_hSwapChainWaitableObject = nullptr;
static ID3D12Resource *g_mainRenderTargetResource[NUM_BACK_BUFFERS] = {};
static D3D12_CPU_DESCRIPTOR_HANDLE g_mainRenderTargetDescriptor[NUM_BACK_BUFFERS] = {};

// Forward declarations of helper functions
bool CreateDeviceD3D(HWND hWnd);
void CleanupDeviceD3D();
void CreateRenderTarget();
void CleanupRenderTarget();
void WaitForLastSubmittedFrame();
FrameContext *WaitForNextFrameResources();
LRESULT WINAPI WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);
using namespace luisa;
using namespace luisa::compute;
static uint2 resolution;
struct ImguiConfig : public DirectXDeviceConfigExt {
    void ReadbackDX12Device(
        ID3D12Device *device,
        IDXGIAdapter1 *adapter,
        IDXGIFactory2 *factory,
        DirectXFuncTable const *funcTable,
        luisa::BinaryIO const *shaderIo,
        IDxcCompiler3 *dxcCompiler,
        IDxcLibrary *dxcLibrary,
        IDxcUtils *dxcUtils,
        ID3D12DescriptorHeap *shaderDescriptor,
        ID3D12DescriptorHeap *samplerDescriptor) noexcept override {
        g_pd3dDevice = device;
    }
    ID3D12CommandQueue *CreateQueue(D3D12_COMMAND_LIST_TYPE type) noexcept override {
        if (type == D3D12_COMMAND_LIST_TYPE_DIRECT)
            return g_pd3dCommandQueue;
        return nullptr;
    }
};

// Main code
int main(int argc, char *argv[]) {
    Context context{argv[0]};
    DeviceConfig config{
        .extension = luisa::make_unique<ImguiConfig>(),
        .inqueue_buffer_limit = false};
    auto device = context.create_device("dx", &config);
    auto draw = device.compile<2>([](ImageFloat image, Float time, UInt2 resolution) noexcept {
        auto p = dispatch_id().xy();
        auto uv = make_float2(p) / make_float2(resolution) * 2.0f - 1.0f;
        auto color = def(make_float4());
        Constant scales{pi, luisa::exp(1.f), luisa::sqrt(2.f)};
        for (auto i = 0u; i < 3u; i++) {
            color[i] = cos(time * scales[i] + uv.y * 11.f +
                           sin(-time * scales[2u - i] + uv.x * 7.f) * 4.f) *
                           .5f +
                       .5f;
        }
        color[3] = 1.0f;
        image.write(p, color);
    });

    // TODO: g_pd3dDevice
    // Create application window
    //ImGui_ImplWin32_EnableDpiAwareness();
    WNDCLASSEXW wc = {sizeof(wc), CS_CLASSDC, WndProc, 0L, 0L, GetModuleHandle(nullptr), nullptr, nullptr, nullptr, nullptr, L"ImGui Example", nullptr};
    ::RegisterClassExW(&wc);
    HWND hwnd = ::CreateWindowW(wc.lpszClassName, L"Dear ImGui DirectX12 Example", WS_OVERLAPPEDWINDOW, 100, 100, 1280, 800, nullptr, nullptr, wc.hInstance, nullptr);

    // Initialize Direct3D
    if (!CreateDeviceD3D(hwnd)) {
        CleanupDeviceD3D();
        ::UnregisterClassW(wc.lpszClassName, wc.hInstance);
        return 1;
    }
    auto stream = device.create_stream(StreamTag::GRAPHICS);
    Image<float> img;
    // Show the window
    ::ShowWindow(hwnd, SW_SHOWDEFAULT);
    ::UpdateWindow(hwnd);

    // Setup Dear ImGui context
    IMGUI_CHECKVERSION();
    ImGui::CreateContext();
    ImGuiIO &io = ImGui::GetIO();
    (void)io;
    io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;// Enable Keyboard Controls
    io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad; // Enable Gamepad Controls
    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;    // Enable Docking
    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;  // Enable Multi-Viewport / Platform Windows
    //io.ConfigViewportsNoAutoMerge = true;
    //io.ConfigViewportsNoTaskBarIcon = true;

    // Setup Dear ImGui style
    ImGui::StyleColorsDark();
    //ImGui::StyleColorsLight();

    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
    ImGuiStyle &style = ImGui::GetStyle();
    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable) {
        style.WindowRounding = 0.0f;
        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
    }

    // Setup Platform/Renderer backends
    ImGui_ImplWin32_Init(hwnd);
    ImGui_ImplDX12_Init(g_pd3dDevice, NUM_FRAMES_IN_FLIGHT,
                        DXGI_FORMAT_R8G8B8A8_UNORM, g_pd3dSrvDescHeap,
                        g_pd3dSrvDescHeap->GetCPUDescriptorHandleForHeapStart(),
                        g_pd3dSrvDescHeap->GetGPUDescriptorHandleForHeapStart());

    // Load Fonts
    // - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them.
    // - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple.
    // - If the file cannot be loaded, the function will return a nullptr. Please handle those errors in your application (e.g. use an assertion, or display an error and quit).
    // - The fonts will be rasterized at a given size (w/ oversampling) and stored into a texture when calling ImFontAtlas::Build()/GetTexDataAsXXXX(), which ImGui_ImplXXXX_NewFrame below will call.
    // - Use '#define IMGUI_ENABLE_FREETYPE' in your imconfig file to use Freetype for higher quality font rendering.
    // - Read 'docs/FONTS.md' for more instructions and details.
    // - Remember that in C/C++ if you want to include a backslash \ in a string literal you need to write a double backslash \\ !
    //io.Fonts->AddFontDefault();
    //io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\segoeui.ttf", 18.0f);
    //io.Fonts->AddFontFromFileTTF("../../misc/fonts/DroidSans.ttf", 16.0f);
    //io.Fonts->AddFontFromFileTTF("../../misc/fonts/Roboto-Medium.ttf", 16.0f);
    //io.Fonts->AddFontFromFileTTF("../../misc/fonts/Cousine-Regular.ttf", 15.0f);
    //ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, nullptr, io.Fonts->GetGlyphRangesJapanese());
    //IM_ASSERT(font != nullptr);

    // Our state
    bool show_demo_window = true;
    bool show_another_window = false;
    ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
    Clock clock;
    // Main loop
    bool done = false;
    while (!done) {
        // Poll and handle messages (inputs, window resize, etc.)
        // See the WndProc() function below for our to dispatch events to the Win32 backend.
        MSG msg;
        while (::PeekMessage(&msg, nullptr, 0U, 0U, PM_REMOVE)) {
            ::TranslateMessage(&msg);
            ::DispatchMessage(&msg);
            if (msg.message == WM_QUIT)
                done = true;
        }
        if (done)
            break;

        // Start the Dear ImGui frame
        ImGui_ImplDX12_NewFrame();
        ImGui_ImplWin32_NewFrame();
        ImGui::NewFrame();

        // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
        if (show_demo_window)
            ImGui::ShowDemoWindow(&show_demo_window);

        // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
        {
            static float f = 0.0f;
            static int counter = 0;

            ImGui::Begin("Hello, world!");// Create a window called "Hello, world!" and append into it.

            ImGui::Text("This is some useful text.");         // Display some text (you can use a format strings too)
            ImGui::Checkbox("Demo Window", &show_demo_window);// Edit bools storing our window open/close state
            ImGui::Checkbox("Another Window", &show_another_window);

            ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
            ImGui::ColorEdit3("clear color", (float *)&clear_color);// Edit 3 floats representing a color

            if (ImGui::Button("Button"))// Buttons return true when clicked (most widgets return true when edited/activated)
                counter++;
            ImGui::SameLine();
            ImGui::Text("counter = %d", counter);

            ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / io.Framerate, io.Framerate);
            ImGui::End();
        }

        // 3. Show another simple window.
        if (show_another_window) {
            ImGui::Begin("Another Window", &show_another_window);// Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
            ImGui::Text("Hello from another window!");
            if (ImGui::Button("Close Me"))
                show_another_window = false;
            ImGui::End();
        }

        if (img && any(img.size() != resolution)) {
            stream.synchronize();
            img = Image<float>();
        }
        if (!img && all(resolution > 0u)) {
            img = device.create_image<float>(PixelStorage::BYTE4, resolution);
        }
        ID3D12Resource *src_img = img ? reinterpret_cast<ID3D12Resource *>(img.native_handle()) : nullptr;
        // Rendering
        ImGui::Render();
        FrameContext *frameCtx = WaitForNextFrameResources();
        // LC-rendering
        if (img) {
            stream << draw(img, clock.toc() * 1e-3f, resolution).dispatch(resolution);
        }
        UINT backBufferIdx = g_pSwapChain->GetCurrentBackBufferIndex();
        frameCtx->CommandAllocator->Reset();
        auto src_state = D3D12_RESOURCE_STATE_PRESENT;
        // Render Dear ImGui graphics

        D3D12_RESOURCE_BARRIER barrier = {};
        barrier.Type = D3D12_RESOURCE_BARRIER_TYPE_TRANSITION;
        barrier.Flags = D3D12_RESOURCE_BARRIER_FLAG_NONE;
        barrier.Transition.pResource = g_mainRenderTargetResource[backBufferIdx];
        barrier.Transition.Subresource = D3D12_RESOURCE_BARRIER_ALL_SUBRESOURCES;
        auto set_state = [&](D3D12_RESOURCE_STATES state) {
            barrier.Transition.StateBefore = src_state;
            barrier.Transition.StateAfter = state;
            src_state = state;
        };
        g_pd3dCommandList->Reset(frameCtx->CommandAllocator, nullptr);
        if (src_img) {
            set_state(D3D12_RESOURCE_STATE_COPY_DEST);
            D3D12_RESOURCE_BARRIER src_barrier = {};
            src_barrier.Type = D3D12_RESOURCE_BARRIER_TYPE_TRANSITION;
            src_barrier.Flags = D3D12_RESOURCE_BARRIER_FLAG_NONE;
            src_barrier.Transition.pResource = src_img;
            src_barrier.Transition.Subresource = D3D12_RESOURCE_BARRIER_ALL_SUBRESOURCES;
            src_barrier.Transition.StateBefore = D3D12_RESOURCE_STATE_COMMON;
            src_barrier.Transition.StateAfter = D3D12_RESOURCE_STATE_COPY_SOURCE;
            {
                D3D12_RESOURCE_BARRIER barriers[] = {barrier, src_barrier};
                g_pd3dCommandList->ResourceBarrier(2, barriers);
            }

            D3D12_TEXTURE_COPY_LOCATION sourceLocation;
            sourceLocation.Type = D3D12_TEXTURE_COPY_TYPE_SUBRESOURCE_INDEX;
            sourceLocation.SubresourceIndex = 0;
            D3D12_TEXTURE_COPY_LOCATION destLocation;
            destLocation.Type = D3D12_TEXTURE_COPY_TYPE_SUBRESOURCE_INDEX;
            destLocation.SubresourceIndex = 0;
            sourceLocation.pResource = src_img;
            destLocation.pResource = g_mainRenderTargetResource[backBufferIdx];
            g_pd3dCommandList->CopyTextureRegion(
                &destLocation,
                0, 0, 0,
                &sourceLocation,
                nullptr);

            std::swap(src_barrier.Transition.StateBefore, src_barrier.Transition.StateAfter);
            set_state(D3D12_RESOURCE_STATE_RENDER_TARGET);
            {
                D3D12_RESOURCE_BARRIER barriers[] = {barrier, src_barrier};
                g_pd3dCommandList->ResourceBarrier(2, barriers);
            }
        } else {
            set_state(D3D12_RESOURCE_STATE_RENDER_TARGET);
            g_pd3dCommandList->ResourceBarrier(1, &barrier);
            const float clear_color_with_alpha[4] = {clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w};
            g_pd3dCommandList->ClearRenderTargetView(g_mainRenderTargetDescriptor[backBufferIdx], clear_color_with_alpha, 0, nullptr);
        }
        g_pd3dCommandList->OMSetRenderTargets(1, &g_mainRenderTargetDescriptor[backBufferIdx], FALSE, nullptr);
        g_pd3dCommandList->SetDescriptorHeaps(1, &g_pd3dSrvDescHeap);
        ImGui_ImplDX12_RenderDrawData(ImGui::GetDrawData(), g_pd3dCommandList);
        set_state(D3D12_RESOURCE_STATE_PRESENT);
        g_pd3dCommandList->ResourceBarrier(1, &barrier);
        g_pd3dCommandList->Close();

        g_pd3dCommandQueue->ExecuteCommandLists(1, (ID3D12CommandList *const *)&g_pd3dCommandList);

        // Update and Render additional Platform Windows
        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable) {
            ImGui::UpdatePlatformWindows();
            ImGui::RenderPlatformWindowsDefault(nullptr, (void *)g_pd3dCommandList);
        }

        g_pSwapChain->Present(1, 0);// Present with vsync
        //g_pSwapChain->Present(0, 0); // Present without vsync

        UINT64 fenceValue = g_fenceLastSignaledValue + 1;
        g_pd3dCommandQueue->Signal(g_fence, fenceValue);
        g_fenceLastSignaledValue = fenceValue;
        frameCtx->FenceValue = fenceValue;
    }

    WaitForLastSubmittedFrame();

    // Cleanup
    ImGui_ImplDX12_Shutdown();
    ImGui_ImplWin32_Shutdown();
    ImGui::DestroyContext();

    CleanupDeviceD3D();
    ::DestroyWindow(hwnd);
    ::UnregisterClassW(wc.lpszClassName, wc.hInstance);

    return 0;
}

// Helper functions
bool CreateDeviceD3D(HWND hWnd) {
    // Setup swap chain
    DXGI_SWAP_CHAIN_DESC1 sd;
    {
        ZeroMemory(&sd, sizeof(sd));
        sd.BufferCount = NUM_BACK_BUFFERS;
        sd.Width = 0;
        sd.Height = 0;
        sd.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
        sd.Flags = DXGI_SWAP_CHAIN_FLAG_FRAME_LATENCY_WAITABLE_OBJECT;
        sd.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
        sd.SampleDesc.Count = 1;
        sd.SampleDesc.Quality = 0;
        sd.SwapEffect = DXGI_SWAP_EFFECT_FLIP_DISCARD;
        sd.AlphaMode = DXGI_ALPHA_MODE_UNSPECIFIED;
        sd.Scaling = DXGI_SCALING_STRETCH;
        sd.Stereo = FALSE;
    }
    {
        D3D12_DESCRIPTOR_HEAP_DESC desc = {};
        desc.Type = D3D12_DESCRIPTOR_HEAP_TYPE_RTV;
        desc.NumDescriptors = NUM_BACK_BUFFERS;
        desc.Flags = D3D12_DESCRIPTOR_HEAP_FLAG_NONE;
        desc.NodeMask = 1;
        if (g_pd3dDevice->CreateDescriptorHeap(&desc, IID_PPV_ARGS(&g_pd3dRtvDescHeap)) != S_OK)
            return false;

        SIZE_T rtvDescriptorSize = g_pd3dDevice->GetDescriptorHandleIncrementSize(D3D12_DESCRIPTOR_HEAP_TYPE_RTV);
        D3D12_CPU_DESCRIPTOR_HANDLE rtvHandle = g_pd3dRtvDescHeap->GetCPUDescriptorHandleForHeapStart();
        for (UINT i = 0; i < NUM_BACK_BUFFERS; i++) {
            g_mainRenderTargetDescriptor[i] = rtvHandle;
            rtvHandle.ptr += rtvDescriptorSize;
        }
    }

    {
        D3D12_DESCRIPTOR_HEAP_DESC desc = {};
        desc.Type = D3D12_DESCRIPTOR_HEAP_TYPE_CBV_SRV_UAV;
        desc.NumDescriptors = 1;
        desc.Flags = D3D12_DESCRIPTOR_HEAP_FLAG_SHADER_VISIBLE;
        if (g_pd3dDevice->CreateDescriptorHeap(&desc, IID_PPV_ARGS(&g_pd3dSrvDescHeap)) != S_OK)
            return false;
    }

    {
        D3D12_COMMAND_QUEUE_DESC desc = {};
        desc.Type = D3D12_COMMAND_LIST_TYPE_DIRECT;
        desc.Flags = D3D12_COMMAND_QUEUE_FLAG_NONE;
        desc.NodeMask = 1;
        if (g_pd3dDevice->CreateCommandQueue(&desc, IID_PPV_ARGS(&g_pd3dCommandQueue)) != S_OK)
            return false;
    }

    for (UINT i = 0; i < NUM_FRAMES_IN_FLIGHT; i++)
        if (g_pd3dDevice->CreateCommandAllocator(D3D12_COMMAND_LIST_TYPE_DIRECT, IID_PPV_ARGS(&g_frameContext[i].CommandAllocator)) != S_OK)
            return false;

    if (g_pd3dDevice->CreateCommandList(0, D3D12_COMMAND_LIST_TYPE_DIRECT, g_frameContext[0].CommandAllocator, nullptr, IID_PPV_ARGS(&g_pd3dCommandList)) != S_OK ||
        g_pd3dCommandList->Close() != S_OK)
        return false;

    if (g_pd3dDevice->CreateFence(0, D3D12_FENCE_FLAG_NONE, IID_PPV_ARGS(&g_fence)) != S_OK)
        return false;

    g_fenceEvent = CreateEvent(nullptr, FALSE, FALSE, nullptr);
    if (g_fenceEvent == nullptr)
        return false;

    {
        IDXGIFactory4 *dxgiFactory = nullptr;
        IDXGISwapChain1 *swapChain1 = nullptr;
        if (CreateDXGIFactory1(IID_PPV_ARGS(&dxgiFactory)) != S_OK)
            return false;
        if (dxgiFactory->CreateSwapChainForHwnd(g_pd3dCommandQueue, hWnd, &sd, nullptr, nullptr, &swapChain1) != S_OK)
            return false;
        if (swapChain1->QueryInterface(IID_PPV_ARGS(&g_pSwapChain)) != S_OK)
            return false;
        swapChain1->Release();
        dxgiFactory->Release();
        g_pSwapChain->SetMaximumFrameLatency(NUM_BACK_BUFFERS);
        g_hSwapChainWaitableObject = g_pSwapChain->GetFrameLatencyWaitableObject();
    }

    CreateRenderTarget();
    return true;
}

void CleanupDeviceD3D() {
    CleanupRenderTarget();
    if (g_pSwapChain) {
        g_pSwapChain->SetFullscreenState(false, nullptr);
        g_pSwapChain->Release();
        g_pSwapChain = nullptr;
    }
    if (g_hSwapChainWaitableObject != nullptr) { CloseHandle(g_hSwapChainWaitableObject); }
    for (UINT i = 0; i < NUM_FRAMES_IN_FLIGHT; i++)
        if (g_frameContext[i].CommandAllocator) {
            g_frameContext[i].CommandAllocator->Release();
            g_frameContext[i].CommandAllocator = nullptr;
        }
    if (g_pd3dCommandQueue) {
        g_pd3dCommandQueue->Release();
        g_pd3dCommandQueue = nullptr;
    }
    if (g_pd3dCommandList) {
        g_pd3dCommandList->Release();
        g_pd3dCommandList = nullptr;
    }
    if (g_pd3dRtvDescHeap) {
        g_pd3dRtvDescHeap->Release();
        g_pd3dRtvDescHeap = nullptr;
    }
    if (g_pd3dSrvDescHeap) {
        g_pd3dSrvDescHeap->Release();
        g_pd3dSrvDescHeap = nullptr;
    }
    if (g_fence) {
        g_fence->Release();
        g_fence = nullptr;
    }
    if (g_fenceEvent) {
        CloseHandle(g_fenceEvent);
        g_fenceEvent = nullptr;
    }
}

void CreateRenderTarget() {
    for (UINT i = 0; i < NUM_BACK_BUFFERS; i++) {
        ID3D12Resource *pBackBuffer = nullptr;
        g_pSwapChain->GetBuffer(i, IID_PPV_ARGS(&pBackBuffer));
        g_pd3dDevice->CreateRenderTargetView(pBackBuffer, nullptr, g_mainRenderTargetDescriptor[i]);
        g_mainRenderTargetResource[i] = pBackBuffer;
    }
}

void CleanupRenderTarget() {
    WaitForLastSubmittedFrame();

    for (UINT i = 0; i < NUM_BACK_BUFFERS; i++)
        if (g_mainRenderTargetResource[i]) {
            g_mainRenderTargetResource[i]->Release();
            g_mainRenderTargetResource[i] = nullptr;
        }
}

void WaitForLastSubmittedFrame() {
    FrameContext *frameCtx = &g_frameContext[g_frameIndex % NUM_FRAMES_IN_FLIGHT];

    UINT64 fenceValue = frameCtx->FenceValue;
    if (fenceValue == 0)
        return;// No fence was signaled

    frameCtx->FenceValue = 0;
    if (g_fence->GetCompletedValue() >= fenceValue)
        return;

    g_fence->SetEventOnCompletion(fenceValue, g_fenceEvent);
    WaitForSingleObject(g_fenceEvent, INFINITE);
}

FrameContext *WaitForNextFrameResources() {
    UINT nextFrameIndex = g_frameIndex + 1;
    g_frameIndex = nextFrameIndex;

    HANDLE waitableObjects[] = {g_hSwapChainWaitableObject, nullptr};
    DWORD numWaitableObjects = 1;

    FrameContext *frameCtx = &g_frameContext[nextFrameIndex % NUM_FRAMES_IN_FLIGHT];
    UINT64 fenceValue = frameCtx->FenceValue;
    if (fenceValue != 0)// means no fence was signaled
    {
        frameCtx->FenceValue = 0;
        g_fence->SetEventOnCompletion(fenceValue, g_fenceEvent);
        waitableObjects[1] = g_fenceEvent;
        numWaitableObjects = 2;
    }

    WaitForMultipleObjects(numWaitableObjects, waitableObjects, TRUE, INFINITE);

    return frameCtx;
}

// Forward declare message handler from imgui_impl_win32.cpp
extern IMGUI_IMPL_API LRESULT ImGui_ImplWin32_WndProcHandler(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);

// Win32 message handler
// You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
// - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
// - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
// Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
LRESULT WINAPI WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam) {
    if (ImGui_ImplWin32_WndProcHandler(hWnd, msg, wParam, lParam))
        return true;

    switch (msg) {
        case WM_SIZE:
            if (g_pd3dDevice != nullptr && wParam != SIZE_MINIMIZED) {
                resolution = uint2((UINT)LOWORD(lParam), (UINT)HIWORD(lParam));
                WaitForLastSubmittedFrame();
                CleanupRenderTarget();
                HRESULT result = g_pSwapChain->ResizeBuffers(0, (UINT)LOWORD(lParam), (UINT)HIWORD(lParam), DXGI_FORMAT_UNKNOWN, DXGI_SWAP_CHAIN_FLAG_FRAME_LATENCY_WAITABLE_OBJECT);
                assert(SUCCEEDED(result) && "Failed to resize swapchain.");
                CreateRenderTarget();
            }
            return 0;
        case WM_SYSCOMMAND:
            if ((wParam & 0xfff0) == SC_KEYMENU)// Disable ALT application menu
                return 0;
            break;
        case WM_DESTROY:
            ::PostQuitMessage(0);
            return 0;
    }
    return ::DefWindowProcW(hWnd, msg, wParam, lParam);
}
